Sleep clock



FIG. 1 is a front view of a sleep clock, showing my new design;

FIG. 2 is a back view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a bottom view thereof;

FIG. 7 is a perspective view thereof; and,

FIG. 8 is another perspective view thereof, shown with the stand in extended condition.

The broken lines in the figures show portions of the sleep clock that form no part of the claimed design. 

CLAIM The ornamental design for a sleep clock, as shown and described. 